The "use mailcard" button fails if the signature in reply is not present

 
If you activate the option "No mailcard on reply and forward" (see image 1)
the "use mailcard" button goes into error (see image 2) if pressed with the need to make the mailcard appear
 
Steps to reproduce:

• activate the option "No mailcard on reply and forward" (see image 1)
• reply to an email (the mailcard is not added)
• click on the button at the top "Use mailcard"

Expected behaviour:

• the mailcard is added

Actual behaviour:

• the mailcard is not added and an error appears (see image 2)